A series of thin, inclined parallel or near parallel layers in a larger
body of rock which form a distinct angle to the principal horizontal bedding
plane. Cross-bedding is found mainly in sandstones
but also in some limestones and conglomerates.
It occurs where sediment is being moved as it is being deposited, building
sand dunes, sand waves, or ripples. It is useful for interpreting ancient
environments as the direction and strength of former currents can be determined
from the pattern and type of structure.
|Crossbedding of sandstone near Mt. Carmel road, Zion
Canyon, Utah, indicating wind action and sand dune formation prior
to formation of rock (NPS photo by George A. Grant, 1929)
AND PLANETARY SCIENCE